The ultimate objective of this research is to determine the etiology and pathogenesis of atherosclerosis and its sequelae. This objective is approached by combining morphologic, experimental, epidemiologic, chemical, immunochemical, cytologic and biometric methods. The possible etiologic relationships of certain environmental factors and disease states to arterial lesions, coronary heart disease and sudden death are being studied using a community pathology approach. This study of a 100 percent sample of deceased men, 24-44 years of age, from the biracial community of New Orleans includes a detailed examination of the heart, coronary arteries, and the postmortem characteristics of the 80 percent of deaths which are autopsied. An explanation for an apparent anomalous difference in coronary heart disease in young Negro and Caucasian men is being sought. Experimental studies in nonhuman primates are being used to study the mechanisms of development and regression of diet-induced arterial lesions. Factors causing variability in rate of development or regression of diet-induced atherosclerotic lesions are being studied. Cholesterol and lipoprotein metabolism is also being investigated in primate animals to obtain an understanding of the mechanisms responsible for the large differences in serum cholesterol or lipoprotein concentration among animals. Archived coronary arteries, aortas, and associated clinical data obtained from 24,000 autopsies from 19 geographic and racial groups are being used to obtain a better understanding of the natural history of human atherosclerosis and its geographic distribution.